Red-Emitting Latex Nanoparticles by Stepwise Entrapment of β-Diketonate Europium Complexes

The core-shell structure of poly(St-co-MAA) nanoparticles containing beta-diketonate Eu3+ complexes were synthesized by a step-wise process. The beta-diketonate Eu3+ complexes of Eu (TFTB)(2)(MAA)P(Oct)(3) [europium (III); 4,4,4-Trifluoro-1-(2-thienyl)-1,3-butanedione = TFTB; trioctylphosphine = (P(Oct)(3)); methacrylic acid = MAA] were incorporated to poly(St-co-MAA). The poly(St-co-MAA) has highly monodispersed with a size of 300 nm, and surface charges of the poly(St-co-MAA) are near to neutral. The narrow particle size distribution was due to the constant ionic strength of the polymerization medium. The activated carboxylic acid of poly(St-co-MAA) further chelated with europium complex and polymerize between acrylic groups of poly(St-co-MAA) and Eu(TFTB)(2)(MAA)P(Oct)(3). The E-m spectra of europium complexes consist of multiple bands of E-m at 585, 597, 612 and 650 nm, which are assigned to D-5(0)-> F-7(J (J = 0-3)) transitions of Eu3+, respectively. The maximum E-m peak is at 621 nm, which indicates a strong red E-m characteristic associated with the electric dipole D-5(0)& RARR;F-7(2) transition of Eu3+ complexes. The cell-specific fluorescence of Eu(TFTB)(2)(MAA)P(Oct)(3)@poly(St-co-MAA) indicated endocytosis of Eu(TFTB)(2)(MAA)P(Oct)(3)@poly(St-co-MAA). There are fewer early apoptotic, late apoptotic and necrotic cells in each sample compared with live cells, regardless of the culture period. Eu(TFTB)(2)(MAA)P(Oct)(3)@poly(St-co-MAA) synthesized in this work can be excited in the full UV range with a maximum E-m at 619 nm. Moreover, these particles can substitute red luminescent organic dyes for intracellular trafficking and cellular imaging agents.

Automated summary

The core-shell structure of poly(St-co-MAA) nanoparticles containing beta-diketonate Eu3+ complexes was successfully synthesized. The nanoparticles exhibited highly monodispersed distribution and near-neutral surface charges. They can serve as a substitute for red luminescent organic dyes for intracellular trafficking and cellular imaging.